Presently, a number of electronics manufacturers are engaged in developing a personal data card which appears similar to a conventional plastic credit card, but additionally contains an electronic circuit, typically comprised of a memory and a microprocessor. The electronic circuit carried by the personal data card enables the card to store large amounts of information, far more than a conventional plastic credit card. Information carried by the card may be accessed and even altered once the card is inserted into a card reader adapted for this purpose. The ability of the personal data card to store large amounts of information makes it useful for many applications. For example, a personal data card could be used as a telephone credit card or a credit card.
An example of a personal data card is disclosed in U.S. Pat. No. 4,649,418, issued on Mar. 10, 1987, to E. Uden. The Uden personal data card is comprised of a PVC card body having at least one aperture sized to receive a carrier body which takes the form of an epoxy glass circuit board. Within the carrier body is a through hole, sized to accommodate a semiconductor chip which has a set of pads thereon, each coupled by a wire lead to a corresponding metallized area on the carrier body adjacent to the through hole. A frame, formed of fiber-reinforced epoxy resin, is placed on the carrier body about the through hole to serve as a dam to contain epoxy encapsulant admitted into the through hole in the carrier body to seal the chip therein. Each of a pair of cover plates is attached to opposite sides of the card body to seal the carrier body within the aperture in the card body.
The Uden personal data card is believed to suffer from the disadvantage that stresses applied to the card during flexing are likely to be transmitted through the card body and into the encapsulant and semiconductor chip, possibly causing chip cracking which will render the card inoperative. The incidence of chip cracking can be lessened by employing semiconductor chips which occupy a small surface area, typically less than 25 square millimeters. However, the amount of data that can be stored in a memory chip decreases when the size of the chip is decreased. Thus, restricting the size of the chip below 25 square millimeters restricts the amount of data that can be stored on the card.
Therefore, there is a need for a personal data card which exhibits reduced incidence of chip cracking without restricting the chip size.